From: Bernd Edlinger <bernd.edlinger@hotmail.de>
Date: Mon, 17 Feb 2025 04:53:09 +0000 (+0100)
Subject: Access cb_items under write_lock in ossl_synchronize_rcu
X-Git-Tag: openssl-3.3.4~168
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=84b0a3a63c9fa29857be4c8c87fc1050d16338fc;p=thirdparty%2Fopenssl.git

Access cb_items under write_lock in ossl_synchronize_rcu

Fixes: 74a52ca9b793 "Don't use __ATOMIC_ACQ_REL on older compilers"

Reviewed-by: Neil Horman <nhorman@openssl.org>
Reviewed-by: Paul Dale <ppzgs1@gmail.com>
Reviewed-by: Tomas Mraz <tomas@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/26790)
---

diff --git a/crypto/threads_pthread.c b/crypto/threads_pthread.c
index 2e2e6121214..06f1ea8855e 100644
--- a/crypto/threads_pthread.c
+++ b/crypto/threads_pthread.c
@@ -514,12 +514,10 @@ void ossl_synchronize_rcu(CRYPTO_RCU_LOCK *lock)
     uint32_t curr_id;
     struct rcu_cb_item *cb_items, *tmpcb;
 
-    /*
-     * __ATOMIC_ACQ_REL is used here to ensure that we get any prior published
-     * writes before we read, and publish our write immediately
-     */
-    cb_items = ATOMIC_EXCHANGE_N(prcu_cb_item, &lock->cb_items, NULL,
-                                 __ATOMIC_ACQ_REL);
+    pthread_mutex_lock(&lock->write_lock);
+    cb_items = lock->cb_items;
+    lock->cb_items = NULL;
+    pthread_mutex_unlock(&lock->write_lock);
 
     qp = update_qp(lock, &curr_id);